Ozone is a colourless or slightly bluish gas (blue when liquefied), made up of three oxygen atoms (O3). It occurs naturally in small (trace) amounts in the upper atmosphere (the stratosphere). Ozone protects life on Earth from the Sun’s ultraviolet (UV) radiation. In the lower atmosphere (the troposphere) near the Earth’s surface, ozone is created by chemical reactions between air pollutants from vehicle exhaust, gasoline vapors, and other emissions. At ground level, high concentrations of ozone are toxic to people and plants. Ground level ozone can also be transported on longer distances in certain meteorological conditions. Organic compounds, released in the forest areas, can influence ozone forming.
Highest ozone concentrations occur in the afternoon hours, as noticeable from the graph, in conditions of high sun radiation. In terms of seasons, highest concentration of this polluting substance is recorded in spring and summer, whereas the lowest concentration is noticed in the winter period. In regard to the environment, this polluting substance causes negative effects on the growth and reproduction of plants, influences ecosystems through changes in the water flow, cycles of minerals/nutrients and habitats and causes disintegration of organic matters.